THE RESPIRATORY EXCHANGE 



493 



for the same infant, when it was eight days old and weighed 

 2650 grm., the respective values were 826 c.c. and 528 c.c. This 

 may be contrasted with the values obtained by Geppert for a 

 man at rest, 264 c.c. of oxygen absorbed and 208 c.c. of carbon 

 dioxide discharged per kilo and hour. 



Babak's results are of great practical importance, for a rapid 

 metabolism necessitates the ready absorption of a perfect food, 

 if the infant is to grow rapidly. The most perfect and the cheapest 

 food is the mother's milk. Artificial feeding is without a doubt 

 the chief cause of the wholesale sacrifice of infant lives, which is 

 to be observed in this country. 



In the child also, as would be expected, the respiratory ex- 



-W4-J 



--- t; < 







FlG. 25. Diagram to Illustrate the Kelation between Volume 

 or Weight and Surface ( Waller.) 



The volumes are . . 1 8 



The weights are . . 1 8 



The surfaces are .6 24 



i.e. their ratio of increase is 1 4 



27 cubic centimetres. 



27 grm. 



54 square centimetres. 



change is relatively much greater than in the adult ; data upon 

 this point will be given in the next section, for the influence of 

 age is closely associated with that of the size of the body. 



In aged subjects the respiratory exchange is relatively smaller 

 than that of the adult ; a result which could be predicted from 

 the diminished activity and muscular tone of the aged. 



Influence of the Size of the Warm-blooded Animal upon its 

 Respiratory Exchange. The larger an animal is, the smaller is 

 the ratio between its surface and its mass, for surface increases 

 as the square and weight as the cube. This important relation 

 between the weight or mass of a body and the extent of its surface 

 is well shown by the diagram given above (Fig. 25), and the 



